Cellular networks provide many services to user equipment (UE) attached to those networks. Example cellular networks can operate in accordance with one or more 3rd Generation Partnership Project (3GPP) standards, including: global system for mobile communication (GSM) enhanced data rates for GSM evolution (EDGE) radio access network (GERAN); universal mobile telecommunications system (UMTS); long term evolution (LTE) including universal terrestrial radio access network (UTRAN); LTE advanced (LTE-A) including evolved UMTS terrestrial radio access network (E-UTRAN). 3GPP release 10, released Q1 2011, and releases 11 and beyond, include, for example specifications for the GERAN, UMTS, LTE and LTE-A families of standards.
Cellular networks generally include a number of cells that provide the UE with a wireless link to the network and its services. A variety of cells can constitute the cellular network. These cell types are generally differentiated by their effective communication ranges. Example, cell types can include macrocells, microcells, picocells, and femotocells. Shorter range cells, such as femtocells, can be used to create localized networks, such as local home networks (LHNs). For example, one or more femtocells can be used in a warehouse to create an LHN servicing the warehouse. A variety of elements, defined in cellular network specifications, support a cell. As used herein, wireless module (e.g., wireless infrastructure module) refers to these discreet elements. In LTE and LTE-A networks, eNBs provide radio access and control. In UMTS networks, nodeBs and radio network controllers (RNCs) are used. In GERAN networks, bases station systems (BSSs) are used. In the warehouse example, under LTE-A, a home eNB (HeNB) is used. BSSs, NodeBs, RNCs, eNBs, and HeNBs are all examples of a wireless module.
A UE can move between cells provoking one or more handover operations between cells and the UE. The LTE and LTE-A specifications include interfaces to facilitate communications between cells. For example, E-UTRAN to E-UTRAN handover can be accomplished via the S1 interface and the X2 interface. E-UTRAN to UTRAN handover can be accomplished via the Iu interface and E-UTRAN to GERAN handover can be accomplished via the A/Gb interfaces.
Packet data network (PDN) access, such as to the Internet, can be a service offered by the cellular network to UE. Example wireless modules that directly or indirectly participate in providing PDN access include, in LTE-A and LTE, MMEs local gateways (L-GWs), PDN gateways (P-GWs) and, in UMTS, gateway general packet radio service (GPRS) support nodes (GGSNs) and server GPRS support nodes (SGSNs). Generally, the cellular network includes a gateway (e.g., L-GW, P-GW or GGSN) to provide the PDN access. Generally, the gateway assigns PDN characteristics to the UE to facilitate this access. When a UE moves from one cell to another, the new cell may not have access to, or it may be inefficient to use, the gateway to the PDN. If the UE has an active PDN session and moves from one cell to another, the PDN connection may need to be deactivated if the target cell will use a different gateway than the gateway responsible for establishing the PDN connection. For example, when a target eNB does not have access to an L-GW used to establish the PDN connection. In an LHN, cells can access the site's local area network (LAN) to provide the PDN access. This is known as local IP access (LIPA). An example of an LTE-A LIPA PDN release procedure, part of the PDN deactivation, is the 3GPP TS 23.401-a21 specification (released Jan. 4, 2011), which defines a mobility management entity (MME) PDN release procedure at clause 5.4.4.2 (MME release procedure). In an example of LIPA PDN release in a 3GPP release 10 system, the local gateway (L-GW) collocated with an eNB can release the LIPA PDN session.